Process and catalyst for preparing 1,4-butanediol

Abstract

The present invention relates to a process for preparing 1,4-butanediol (BDO) by hydrogenating 2-butyne-1,4-diol (BYD) or 4-hydroxybutanal (4-HBA) in the presence of a catalyst of the Raney type having a porous foam structure, wherein the macroscopic pores have sizes in the range of 100 to 5000 μm, and a bulk density of up to 0.8 kg/L.

Claims

1. A process for preparing 1,4-butanediol by hydrogenating 2-butyne-1,4-diol or 4-hydroxybutanal, said method comprising contacting an aqueous solution comprising 2-butyne-1,4-diol or 4-hydroxybutanal with hydrogen and an activated nickel catalyst, wherein said activated nickel catalyst comprises: a) a porous foam structure; b) macroscopic pores in the range of 100 to 5000 μm; c) a bulk density of not more than 0.8 kg/L.

2. The process of claim 1, wherein the hydrogenation of 4-hydroxybutanal is carried out at a hydrogen pressure in the range of 10 to 110 bar.

3. The process of claim 2, wherein the hydrogenation is carried out in a temperature range of 50 to 200° C.

4. The process of claim 1, wherein the hydrogenation of 2-butyne-1,4-diol is carried out at a hydrogen pressure in the range of 50 to 350 bar and a temperature range of 50 to 150° C.

5. The process of claim 1, wherein said process is carried out in a fixed bed reactor.

6. The process of claim 5, wherein the fixed bed reactor is operated adiabatically, with a temperature at the reactor inlet in the range of 80 to 100° C. and a temperature at the reactor outlet in the range of 110 to 150° C.

7. The process of claim 6, wherein the activated nickel catalyst has an aluminum content of not more than 15% by weight.

8. The process of claim 7, wherein the activated nickel catalyst comprises macroscopic pores with sizes in the range of 200 to 2500 μm.

9. The process of claim 5, wherein the process is carried out continuously in a trickle bed reactor, liquid-filled reactor, or a bubble column.

10. The method of claim 5, wherein the fixed bed reactor is operated in a “once through” mode, in which the reactants are introduced into the reactor and the product mixture is removed after the reaction.

11. The process of claim 1, wherein the activated nickel catalyst comprises 0 to 10% by weight of at least one of the elements selected from the group consisting of: molybdenum, iron, and chromium.

12. The process of claim 11, wherein the hydrogenation is carried out continuously.

13. The process of claim 12, wherein the activated nickel catalyst has an aluminum content of not more than 15% by weight.

14. The process of claim 13, wherein the activated nickel catalyst has a porous foam structure, wherein the macroscopic pores have sizes in the range of 200 to 2500 μm.

15. The process of claim 1, wherein the hydrogenation is carried out batchwise in a stirred tank reactor using a two temperature reaction regime, wherein: a) the temperature in the stirred tank at the start of the reaction is maintained in the range of 90 to 105° C. so that 2-butyne-1,4-diol is reacted with hydrogen to give 2-butene-1,4-diol; b) after uptake of hydrogen stoichiometrically equivalent to the amount of 2-butyne-1,4-diol used, the first reaction stage is concluded and the temperature in the stirred tank is then increased to 130 to 135° C. and maintained in that range until completion of the hydrogenation to give 1,4-butanediol.

16. The process of claim 15, wherein the catalyst is arranged in a holding device close to the stirrer shaft such that a flow of the reaction mixture through the catalyst bed is generated by the stirrer.

17. The process of claim 15, wherein the hydrogenation of butyne-1,4-diol is carried out at a hydrogen pressure in the range of 50 to 350 bar.

18. The process of claim 17, wherein the activated nickel catalyst has an aluminum content of not more than 15% by weight.

19. The process of claim 15, wherein the activated nickel catalyst comprises macroscopic pores with sizes in the range of 200 to 2500 μm.

20. The process of claim 15, wherein the activated nickel catalyst comprises 0 to 10% by weight of at least one of the elements selected from the group consisting of: molybdenum, iron, and chromium.

Description

EXAMPLE 1

(1) A nickel foam commercially available in rolls and having a thickness of 1.9 mm, a width of 300 mm and an average pore size of 580 μm was sprayed with a commercially available adhesion promoter solution, coated with aluminium powder and subjected to a heat treatment at 700° C. After cooling the material thus obtained was cut with a laser into square pieces having an edge length of 4 mm×4 mm and a thickness of 1.9 mm.

(2) The resulting loose material was arranged in a fixed bed for the catalytic activation and subsequently wet-chemically treated by pumping through 5M NaOH solution (aqueous sodium hydroxide solution). A portion A of the loose material was subjected to this wet-chemical post-treatment at 70° C. for a period of 5 minutes. A portion B of the loose material was post-treated at 60° C. with aqueous sodium hydroxide solution for a period of 15 minutes.

(3) Both portions were subsequently washed with water until a pH<10 of the wash solution after pumping through the fixed bed had been reached.

(4) The composition of the two catalytically active loose material portions thus obtained was analysed by ICP-OES. The results are compiled in the following table:

(5) TABLE-US-00001 Catalyst Nickel content Aluminium content Bulk density A 85.8 wt % 14.1 wt % 0.5 kg/L B 85.3 wt % 14.7 wt % 0.5 kg/L

(6) The bulk densities specified in the table above were determined by slow addition of a defined amount of the drop-wet catalyst to a 1 L standard measuring cylinder filled with water. After settling of the catalyst is complete, the volume of the catalyst bed is read off the scale. The bulk density d.sub.Sch is calculated according to the equation
d.sub.Sch=M.sub.F/V.sub.F

(7) where M.sub.F is the amount of catalyst used in the dry mass and V.sub.F is the volume of the bed observed under water. The dry mass of the activated catalyst is determined by comparative weighing of a container of defined volume, which is filled with water and catalyst, to a container of the same volume, which is filled only with water. The mass of the dry catalyst is given by the difference of the two weights multiplied by a density factor k, which is derived from the quotient of the density of the dry catalyst and the difference in density between the thy catalyst and water. Density factors can be taken directly from the technical literature and/or the handling instructions of the manufacturers and distributors of catalysts of the Raney type and are typically about 1.2. The volume of the catalyst bed is directly accessible to those skilled in the art by reading off the scale of the measuring cylinder used. The method is independent of the particle size of the Raney type catalyst, i.e. independent of whether they are beds of granular or foam material or are powder catalysts under water.

(8) Catalyst A was introduced into a stirred tank reactor with a total volume of 500 ml in order to investigate the catalytic efficacy in the hydrogenation of butyne-1,4-diol (BYD) to 1,4-butynediol (BDO). 300 mL of water were initially charged in the reactor, 5 mL of catalyst A were introduced 2.0 into a basket positioned below the water level close to the stirring shaft. After closing the reactor, atmosphere exchange and filling the reactor with hydrogen up to a pressure of 80 bar, 86.6 g of BYD in 50% aqueous solution were pumped into the reactor with stirring and the reactor was heated to 100° C. After a reaction time of 100 minutes, the temperature in the reactor was increased to 135° C. and maintained for a further 260 minutes. After cooling to room temperature, a sample of the reaction mixture was removed and analysed by gas chromatography. From the measured concentrations of the constituents of the reaction mixture, the butynediol conversion, the yield to give BDO and the selectivity for BDO, and also the space-time yield STY.sub.BDO,V based on the catalyst volume were determined. The results are compiled in the following table:

(9) TABLE-US-00002 BYD Yield Selectivity conversion of BDO for BDO STY.sub.BDO, V 97% 86% 89% 1.30 kg/(L cat*h)

(10) The quantities stated are calculated as follows: BYD conversion is defined as the molar amount of BYD consumed based on the molar amount of BYD used:

(11) $U_{\mathrm{BYD}}\left[\%\right]=\frac{n_0\left(\mathrm{BYD}\right)-n\left(\mathrm{BYD}\right)}{n_0\left(\mathrm{BYD}\right)}*100,$ where n.sub.0 (BYD)=molar amount of BYD used and n (BYD)=molar amount of BYD at the end of the reaction yield of BDO is defined as the molar amount of BDO obtained based on the molar amount of BYD used:

(12) $Y_{\mathrm{BDO}}\left[\%\right]=\frac{n\left(\mathrm{BDO}\right)}{n_0\left(\mathrm{BYD}\right)}*100$ selectivity for BDO is defined as the ratio of the amount of desired product BDO formed to the amount of reactant BYD converted:

(13) $S_{\mathrm{BDO}}\left[\%\right]=\frac{n\left(\mathrm{BDO}\right)}{n_0\left(\mathrm{BYD}\right)-n\left(\mathrm{BYD}\right)}*100$ the catalyst volume-based space-time yield is defined as the production output based on the volume of catalyst (in litres), where production output is understood to mean the mass of desired BDO product (in kg) generated per reaction run based on the reaction time t (in hours

(14) ${\mathrm{STY}}_{\mathrm{BDO},V}=\frac{m\left(\mathrm{BDO}\right)}{V_{\mathrm{cat}}*t}$

EXAMPLE 2

(15) A catalyst was prepared as described in example 1, wherein the wet-chemical post-treatment was carried out with 10% by weight aqueous sodium hydroxide solution at 60° C. for a period of 60 minutes. Analysis by ICP-OES gave a composition of the resulting catalytically active bulk material (catalyst C) of 89% by weight nickel and 11% by weight aluminium. The material had a bulk density of d.sub.Sch=0.3 kg/L. The bulk density was determined according to the procedure described in example 1.

(16) Catalyst C was also investigated for its catalytic efficacy in the hydrogenation of butyne-1,4-diol (BYD) to 1,4-butanediol (BDO) in a stirred tank reactor. Experimental setup, procedure and evaluation were carried out as described in example 1.

(17) The results are compiled in the following table:

(18) TABLE-US-00003 BYD Yield Selectivity conversion of BDO for BDO STY.sub.BDO, V 97% 90% 93% 1.37 kg/(L cat*h)

(19) From the bulk density of catalyst C and the catalyst volume-based space-time yield, the space-time yield STY.sub.BDO,m based on the catalyst mass could be calculated as follows:
STY.sub.BDO,m=STY.sub.BDO,v/d.sub.Sch
It was STY.sub.BDO,m=4.55 kg/(kg cat*h).

EXAMPLE 3

(20) A catalyst was prepared as described in example 1, wherein the wet-chemical post-treatment was carried out with 10% by weight aqueous sodium hydroxide solution at 80° C. for a period of 90 minutes. After completion of the wet-chemical treatment with aqueous sodium hydroxide solution, molybdenum was precipitated on the catalyst from an aqueous molybdate solution. Analysis by ICP-OES gave a composition of the resulting catalytically active bulk material (catalyst 0) of 91% by weight nickel, 8.7% by weight aluminium and 0.3% by weight molybdenum. The material had a bulk density of d.sub.Sch=0.32 kg/L. The bulk density was determined according to the procedure described in example 1.

(21) Catalyst D was used in a pilot fixed bed reactor for the hydrogenation of 4-hydroxybutanal (HBA) to BDO at a temperature of 60° C. and a hydrogen pressure of 100 bar and showed virtually quantitative HBA conversion with very good BDO yields and selectivities for BDO.

COMPARATIVE EXAMPLE

(22) An activated nickel catalyst of the granulate type was prepared, as known from the prior art, e.g. DE 2004611A, and used in customary industrial plants for preparing BDO. To this end, by melting nickel and aluminum, an alloy consisting of 42% by weight nickel and 58% by weight aluminum was produced, subjected to mechanical comminution and sieved to obtain a grain fraction having a particle size of 1.8 to 4 mm. This alloy pellet fraction was catalytically activated in a loose fill fixed bed by pumping a 10% by weight aqueous sodium hydroxide solution therethrough at 60° C. for a duration of 60 minutes and subsequently washing with water until a pH of the resulting washing solution of <10 had been achieved. The resulting catalyst had a bulk density of d.sub.Sch=1.7 kg/L. The bulk density was determined according to the procedure described in example 1. The aluminium content was approximately 37% by weight aluminium.

(23) This catalyst according to the prior art was also investigated for its catalytic efficacy in the hydrogenation of butyne-1,4-diol (BYD) to 1,4-butanediol (BDO) in a stirred tank reactor. Experimental setup, procedure and evaluation were carried out as described in example 1. The results are compiled in the following table:

(24) TABLE-US-00004 BYD Yield Selectivity conversion of BDO for BDO STY.sub.BDO, V 97% 85% 88% 1.29 kg/(L cat*h)

(25) From the bulk density of the catalyst according to the prior art and the catalyst volume-based space-time yield, the space-time yield STY.sub.BDO,m based on the catalyst mass could be calculated. It was 0.75 kg/(kg cat*h).

(26) The results obtained in the stirred tank experiments for the catalysts A (from example 1) and C (from example 2) are compared with the characteristics obtained using the catalyst according to the prior art (comparative example): at constant conversion, catalyst A shows a slight improvement, catalyst C shows a considerable improvement in BDO yield and selectivity for BDO.

(27) Also, the space-time yields based on the catalyst mass which were achieved using the catalyst of the granulate type according to the prior art (comparative example) and the inventive catalyst C are compared. Clearly recognizable is a six-fold increase in the value for inventive catalyst C compared to the prior art.

(28) The resultant amounts saved of nickel for an industrial fixed bed reactor is calculated below as an example of a typical BDO reactor comprising 20 m.sup.3 of catalyst bed.

(29) In around-the-clock continuous operating mode, such a plant is operated productively on average for at least 8000 operating hours per year. At a catalyst volume-based space-time yield of 1.29 kg/(L cat*h)=1.29 t/(m.sup.3 cat*h) for the nickel catalyst of the granulate type according to the prior art (comparative example), an annual amount of BDO produced results therefrom of 1.29×20×8000 t=206400 t of BDO. Using the catalyst according to the prior art, which has a bulk density of 1.7 kg/L=1.7 t/m.sup.3 at a nickel content of 60-65% by weight, at least 20×1.7×0.6 t=20.4 t of nickel are required therefor.

(30) In order to produce the same amount of BDO over catalyst C of example 2, which has a catalyst volume-based space-time yield of 1.37 kg/(L cat*h)=1.37 t/(m.sup.3 cat*h), 206400/(1.37*8000) m.sup.3 18.83 m.sup.3 of catalyst are required. This corresponds to a catalyst volume saving of 1.17 m.sup.3 of catalyst or 5.85%. The amount of catalyst C required at a bulk density of inventive catalyst C of 0.3 kg/L=0.3 t/m.sup.3 is 18.83×0.3 t=5.649 t of catalyst C. This corresponds at a nickel content of 89% by weight to a nickel requirement of 5 t compared to a nickel requirement of at least 20.4 t using catalyst of the granulate type according to the prior art.

(31) Therefore, the amount of nickel required can be reduced to ¼ of the current usual amount by means of the process according to the invention, by which means an extremely efficient process for 2.0 preparing 1,4-butanediol is provided.